P0945Generic code

P0945 Code: Hydraulic Pump Relay Circuit Open

The P0945 code means the control circuit of the hydraulic pump relay is open, so the component gets no current when the computer commands it. That can lead to a loss of hydraulic pressure and a gearbox that stops shifting. Check the fuse, the relay, the connector and the wiring before replacing anything.

Severity
High
Can I keep driving?
Yes, but with caution
Estimated cost
$100 to $1,200
Difficulty
Medium
System
Transmission
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

On this page

What the P0945 code means

Automated manual transmissions (Opel Easytronic, Fiat Dualogic, Toyota MMT, BMW SMG, Ford Durashift, Volkswagen ASG) and many dual-clutch gearboxes use electric or hydraulic actuators to release the clutch, pick the gear plane (selection) and engage the gear (engagement). The transmission computer watches every actuator through position sensors. In hydraulic systems, an electric pump keeps up the accumulator pressure that operates the clutch and the shifts, and the computer turns it on through a relay.

The computer monitors the control circuit from its own driver transistor. The P0945 code means the circuit is open: the component receives no current when it is commanded on. Before you change the component, check the fuse, the relay, the connector and the wiring, because those are the usual culprits.

If the pump does not run, the system loses pressure and the gearbox stops shifting. If the relay sticks closed, the pump runs nonstop and overheats. After any repair on these parts, the gearbox learning procedures (clutch touch point, selection positions and engagement positions) have to be run with a scan tool. Without them the transmission will not work properly.

Measure the resistance of the component at its connector: infinite means it is open inside. If it reads correctly, follow the control wire back to the computer and look for a break, particularly in the stretches close to the exhaust and at in-line connectors.

P0945 code symptoms

  • Check engine light or another warning light on.
  • Loss of hydraulic pressure.
  • The gearbox will not engage gears or stays in neutral.
  • Transmission or engine light on.
  • Beep or warning message on the dash.

Likely causes of the P0945 code

  1. Connector unplugged or with a broken lock.
  2. Open coil. Infinite resistance.
  3. Cut wire. Check the places where the harness rubs.
  4. Blown fuse. Often the result of an earlier short.

How to diagnose the P0945 code step by step

  1. Command the component with the scan tool and see whether it responds.
  2. Check the fuse and the relay. Measure voltage on both sides of the fuse and swap the relay with an identical one.
  3. Measure the supply at the connector. You should see battery voltage with the key on, or when the component is commanded.
  4. Measure the component resistance and compare it with the manual, then check the insulation to ground.
  5. Check the control wire for continuity to the computer and for shorts.
  6. Command the actuator with the scan tool and see whether it moves.
  7. Run the gearbox learning procedures after any repair.
  8. Check the hydraulic fluid level and look for leaks.

How to fix the P0945 code

  • Repair the connector, the wiring or the supply.
  • Replace the hydraulic pump relay if it does not respond when it has the right supply and command.
  • Clear the P0945 code and verify the repair.

Technical reference data

  • Electric actuator (DC motor) or hydraulic solenoid valve controlled by PWM.
  • Reference values only: check the manufacturer data for your vehicle.

Brand-specific notes

These are the makes where this family of codes shows up most. In many hydraulic systems the actuator fluid is a specific one, and the reservoir should be checked regularly.

P0945 on Opel

Very common on the Opel Easytronic.

P0945 on Fiat

Very common on the Fiat Dualogic.

P0945 on Toyota

Very common on the Toyota MMT.

P0945 on Smart

Very common on Smart cars with this style of transmission.

P0945 on BMW

Very common on the BMW SMG.

Frequently asked questions about P0945

Can I drive with a P0945 code?
With caution, and only as far as a shop. The gearbox can lose its gears at any moment.
What does the hydraulic pump relay do?
Automated manual transmissions (Opel Easytronic, Fiat Dualogic, Toyota MMT, BMW SMG, Ford Durashift, Volkswagen ASG) and many dual-clutch gearboxes use electric or hydraulic actuators to release the clutch, pick the gear plane (selection) and engage the gear (engagement). The transmission computer watches each actuator with position sensors. In hydraulic systems, an electric pump keeps up the accumulator pressure that operates the clutch and the shifts, and the computer switches it on through a relay.
Does the part always have to be replaced?
No. Check the fuses, relays, connectors and wiring first, since they cause most of these faults.
How much does it cost to fix P0945?
As a rough guide, between $100 and $1,200. A fuse or connector is cheap, and a pump or actuator with labor costs more.
What does the P0945 code mean?
It means the pump relay control circuit is open. The relay gets no command current from the computer, so the pump may never start.
What is the most common cause of P0945?
A loose or broken connector, especially after another repair in the area. A cut wire and a blown fuse come next.

Related codes

Questions about the P0945 code

There are no questions about this code yet. Tell us about your case: vehicle, symptoms and what you have already checked.